An optical transport network serves for the backbone transport in telecom networks. Signal transmission is typically based on time division multiplexing. The ITU has defined in G.709 a standard for the Optical Transport Network. The initial version of G.709 provided three levels of multiplexing, which were termed Optical Data Units ODU1, ODU2, and ODU3, with data rates of 2.5 Gb/s, 10 Gb/s, and 40 Gb/s, respectively. At each multiplexing level, a corresponding framed signal structure including section overhead and FEC bytes was defined, which were termed Optical Transport Units OTU1, OTU2, and OTU3. An OTU2 for example can carry either one ODU2 or four ODU1. Later, a lower size multiplexing level ODU0 with a capacity of 1.25 Gb/s was defined to support transport of Gigabit Ethernet signals, where an OTU1 can carry two ODU0. Additionally, a data unit called ODUflex allows to flexibly adjust the container size in increments of 1.25 Gb/s timeslots (TS). No transport frame is defined, however, for ODU0 and ODUflex containers, so these can only occur as lower order data units multiplexed within an OTU1 or higher transport frame.